Method of bleaching wood pulp



Aug. 16 1927.

1,638,886 F'. G'. SHERBONDY ET AL METHOD OF' BLEACHING WOOD PULP FiledFeb. 21. 1925 2 Sheets-Sheet 1 H H Hlllllllllmlpllm WWUHHUUI HHHIlmlilllllm n 1,638,886 Away 15, 1927' F, G, sHERBONDY ET A'- METHOD 0FBLEACHING WOOD PULP Filed Feb. 21. 1925 2 Sheets-Sheet 2 lulerbo .7l/@wc:Boe/Uw,

Patented Aug. 16, y192,7.

UNITED STATES i l l 1,888,888 PATENT OFFICE.

FREDERICK e. sHnnBoNDY, or AKRON, OHIO, AND MAX n. Bonnin, or ArrLn'rON,

WISCONSIN. f -v METHOD Aor BLEACHING WOOD Prim.

f! i Application led February 21,11/925 Serial No. 10,811.

4The object of our invention .is to provide a novel apparatus and methodfor bleaching, under pressure, wood pulp at a highconsistency, theinvention being adapted, however, for use'in'connection with thebleaching of `other materials.

'lore specifically, the method resides in agitating and mixing thestock, at high consistency, and under pressure, with the bleach liquor,in a closed container, Without the application of heat; and, by thiscold bleaching, under pressure, of the stock, at a high consistency, a`much tougher grade of'work is secured than is possible inAhot-bleaching,

" 'which has a tendency to weaken the fibres of the stock. Anotheradvantage of this method of bleaching in a closed, air-tight container,-is that escape of chlorine gas is prevented, thereby economizing in thecost of practising the method.

YThe Aapparatus resides in a closed container or retort, which isconstructed so as to be pressure tight -and thus retain all the chloringases, and whereby the pressure of the gases evolved'in the retort makesit possible, to secure a better penetration of the bleach liquor intothe stock.' The invention also resides in providing the retort,inteniorly, with baffles, so arranged that it is possible to thoroughlymix the stock at a high consistency.

An apparatus capable of practising the method is disclosed in theaccompanying drawings, in which like reference-characters denotecorresponding structural parts in the several views. Briefly described:

Figure l is a view in side elevation of our retort or engine;

Figure 2 is a view in end elevation thereof;

Figure 3 .is a view in top plan of the retort removed from itssupporting pillars; and

Figure 4r is a view in section, taken upon the plane of the section linel-h indicated in Fig. 1, looking in the direction ci the arrows shown inconnection therewith.

Referring, now, in detail to the drawings:

l indicates, in general, our ,globe rotary bleaching engine, which i-sconstructed pressure proof and air-tight, so as to prevent 'escape ofchlorine gas in the operation thereof, and which is provided with aman-hole 2 tightly closed by a cover 3 when t-he engine is inoperation,` and with a valve 4, said cover and valve being preferablydisposed at da-metrica-lly-Opposite points on the engine.

The engine is also provided with tru'nnions 5, 5, rotatably supported inbearings at the top of pillars 6, 6. y

, Fast Aon one of said trunnions. is a gearwheel 7 meshing `with agear-train driven from a suitable source of power, whereby the engine orretort may be revolved. at thespeed desired.

Interiorly, the globe l is provided with equidistantly spaced pairs ofwings 8, 8, each pair being, roughly, bow-shaped, as shown. These wingsconstitute agitators or baiiles, which agitate and mix the stock withthe bleach liquor. Referring to the drawing it will be seen'that thewing-shaped ballles are not all arranged -alike,.but are so arrangedthat the point`or the apex of adjacent baffles point in oppositedirections With respect to the direction of rotation, that is, one setof alternate ballles point yin the direction of rotation while the otherset of bales point in the opposite direction to that of rotation. By theconstruction described, it iso possible to expeditiously mix stock, athigh consistency, with the bleach liquor, and to carry on the bleachingoperation under pressure.

This pressure may be gas evolved from the chlorine used in the bleachingliquor, or such pressure may be supplemented, as required, by otherforms of gas, or by water, or by steam forced into the rotary bleaehelvor retort. The action of the apparatus is as follows:

The rotation of the globe tends to raise the pulp on the rip-turningside of the charnber and to cause it to flow back towards the lowerrnostpoint of the globe. This causes the pulp to move continuously in arolling or as to'. cause alternate concentrating and spreading` of theflow. It will be seen that as a baille point-ing away from the directionof rotation passes through t-he stock, it will carry a portion of themixture along in front of it, and as it begins its upward travel thesides of the baile form a pocket-like element and direct the flowtowards the point Of the batile,'where it will pass over the upper edgein a concentrated stream. But with respect to an adjacent balle,the'sides will act as dellectors for the stream and will cause the stockto spread out and pass over sure, in a closed retort, there is no lossof the bleach liquor or gases, resulting in a substantial saving overcustomer methods :of bleaching in an open receptao e. Since the retortis pressure-proof, the gases generated in the bleaching operation areconinedjta d the pressure thereof makes it possible to 'get a betterpenetration of the" liquor into the q stock.

Having thus fully described our invention, what We claim as new anddesire to secure by Letters-Patent of the United States is:

l. The method of bleaching pulp which consists in enclosing a mixture ofpulp and bleaching liquor within a sealed spherical container, andagitating the mixture by subjecting it to alternate spreading andconcentrating flow action. v

2. The metlr'ri'of bleaching pulp which consists in encl` sing a mixtureof pulp and bleaching liquor within a sealed container, agitating themixture by causing it to flow continuously in one direction withalternate spreading and concentrating action.

3. The method 4of bleaching pulp which consists in enclosing a mixtureof pulp and bleaching liquor within a sealed spherical container, andagitating the mixture by subjecting it to a rolling flow towards acommon point.

4. The method of bleaching pulp wliich consists in admitting a mixtureof ulp and bleaching liquor to a spherical cham er, sealing the chamber,subjecting the mixture to pressure, agitating the mixture by rotatingthe chamber and causing the flow of the mixture to alternately s readand concentrate.

5. The method o bleaching pulp which consists in admitting a mixture ofulp and bleaching liquor to a spherical cham er,'seal' ing the chamber,subJecting the mixture to' pressure, agitating the mixture by rotatingthe chamber continuously in one direction and causing the flow of themixture to alternately spread and concentrate.

v In testimony whereof, We affix our signatures.

FREDERICK G. sHERBoNDY. MAX E. Bo-EHM.

